“Pre universal vaccination, there were roughly 15,000 pediatric cases of hepatitis B every year,” says Sean T. O’Leary, a professor of pediatrics and a pediatric infectious diseases specialist at the University of Colorado Denver Anschutz Medical Campus and Children’s Hospital Colorado. He is also the chair of the Committee on Infectious Diseases of the American Academy of Pediatrics (AAP). “Roughly 90% of those went on to develop chronic hepatitis, and of those, about a quarter ended up dying from the disease. With universal vaccination, perinatal and pediatric cases of hepatitis B have been extraordinarily rare.”